Magnesium Alloys for Space Hardware Design

There have been advances in magnesium alloy development that NASA has not taken into consideration for space hardware because of a lack of test data. Magnesium alloys offer excellent weight reduction, specific strength, and deep space radiation mitigation. Traditionally, magnesium has been perceived as having too poor of a flammability resistance and corrosion resistance to be used for flight. Recent developments in magnesium alloying has led to the formation of two alloys, WE43 and Elektron 21, which are self-extinguishing and significantly less flammable because of their composition. Likewise, an anodizing process called Tagnite was formulated to deter any concern with galvanic and saltwater corrosion. The Materials Science Branch at Kennedy Space Center is currently researching these new alloys and treatments to better understand how they behave in the harsh environment of space. Successful completion of the proposed testing should result in a more thorough understanding of modern aerospace materials and processes, and possibly the permission to use magnesium alloys in future NASA designs

Observations and Validation of Plasma Density, Temperature, and O+ Abundance From a Langmuir Probe Onboard the International Space Station

The Floating Potential Measurement Unit (FPMU) has been operational on board the International Space Station (ISS) since 2006. One of the instruments in the FPMU suite is a spherical wide-sweeping Langmuir probe, referred to as the WLP, which is sampled at a temporal cadence of 1 s giving in-situ measurements of the plasma density and electron temperature. In this study we present our refinements to the Langmuir probe analysis algorithm that address the uncertainties associated with photoelectron emission current from the metal probe. We also derive the fraction of O+ ions as a secondary data product, which shows decrease in O+ abundance in the post-midnight sector during solar minimum. The derived plasma parameters are compared and validated with an independent in-situ measurement technique, overlapping ground-based incoherent scatter radar measurements, as well as International Reference Ionosphere model output. The reduced data set spans the entire solar cycle 24 and shows the F-region ionosphere variance at ISS altitudes

Development and Flammability Testing of Magnesium Alloys for Space Applications

This project will be comparing the flammability of select lightweight Mg alloys for use in a simulated ISS environment. It will also be determining the factors that influence flammability of selected alloys in elevated oxygen, including the formation of an oxide layer. The significance of this work is that such alloys can reduce weight saving by up to 30%. This work is adding to knowledge base of lightweight Mg alloys for possible future applications, as no previous flammability testing of Mg alloys have been conducted at elevated oxygen concentrations

Improved Tracking of Resident Space Objects Using the ERAU OSCOM System

Optical and Spectral characterization of CubeSats for Operational Missions (OSCOM) is a system that uses custom software and inexpensive commercial off the shelf (COTS) equipment to perform space situational awareness tasks for resident space objects (RSO), such as photometry and resolved imaging of larger satellites. Current version of the OSCOM software includes two program pieces: Pre-Tracking and Tracking. The Pre-Tracking program obtains two-line orbital elements (TLE) of satellites and propagates their paths to display the list of objects that are passing over the specified location during the selected time period. This list of satellites is presented on a Graphical User Interface (GUI) and can be customized by utilizing filters such as illumination, satellite and orbit types. The Tracking part of the program is capable of performing satellite imaging, and then commanding the telescope mount to follow the propagated path. This software piece also features the GUI that allows the user to control the tracking process. Additionally, another program has been in development, which focuses on the implementation of the optical feedback. The optical feedback is required for future versions of the OSCOM software that is planned to operate completely autonomously. The implementation of the optical feedback within OSCOM has been heavily dependent upon interfacing with the camera and getting proper function of tracking equipment during TLE assisted tracking. The optical feedback is yet to be field tested, but its use on previously recorded image data to shows that satellites were recognized by object detection algorithms

Observations and Validation of Plasma Density, Temperature, and O+ Abundance From a Langmuir Probe Onboard the International Space Station

The Floating Potential Measurement Unit (FPMU) has been operational on board the International Space Station (ISS) since 2006. One of the instruments in the FPMU suite is a spherical wide-sweeping Langmuir probe, referred to as the WLP, which is sampled at a temporal cadence of 1 s giving in-situ measurements of the plasma density and electron temperature. In this study we present our refinements to the Langmuir probe analysis algorithm that address the uncertainties associated with photoelectron emission current from the metal probe. We also derive the fraction of O+ ions as a secondary data product, which shows decrease in O+ abundance in the post-midnight sector during solar minimum. The derived plasma parameters are compared and validated with an independent in-situ measurement technique, overlapping ground-based incoherent scatter radar measurements, as well as International Reference Ionosphere model output. The reduced data set spans the entire solar cycle 24 and shows the F-region ionosphere variance at ISS altitudes

Martensite decomposition during rapid heating of Ti-6Al-4V studied via in situ synchrotron X-ray diffraction

Abstract Martensite, α‘, commonly appears in Ti-6Al-4V upon rapid cooling from above the β-transus temperature. It is known that α‘ decomposes into α and β at high temperatures but well below the β-transus temperature. Here, we study the decomposition of martensitic Ti-6Al-4V under rapid laser heating, employing in situ synchrotron X-ray diffraction. A comparison is made with post-annealed Ti-6Al-4V under heating to elucidate changes without martensite decomposition. The fast acquisition of X-ray diffraction data at 250 Hz temporally resolves the decomposition process initiated by annihilating dislocations in α‘. The recovery process is accompanied by structural changes in martensite, followed by the phase transformation to β. Thermal profiles estimated from the lattice parameter data reveal the influence of heating rates and dislocation densities on the decomposition process. Throughout the analysis of the diffraction profiles with respect to estimated temperature, we propose a straightforward method for approximating the initiation temperature of martensite decomposition